Although it is well established that the central nervous system participates in the regulation of reproductive function in man, complete information regarding the neural mechanisms regulating pituitary secretion of luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin is still lacking. Of major importance in understanding the relationship between the CNS and pituitary hormone secretion is a clarification of which neurotransmitters are involved in releasing the hypothalamic neurohormones. Several amino acids acting as neurotransmitters in the mammalian nervous system are present in high concentrations in the hypothalamus. Recent studies from this laboratory have shown that several of these, GABA, lysine, glutamate, beta-alanine, and taurine can influence pituitary hormone secretion in male animals. The objective of this proposal is to ascertain more fully the role of neurally excitant amino acids in reproductive processes in both the male and female. The study will investigate the involvement of the amino acids in the control of reproductive hormone secretion, and in age related changes in the reproductive system, specifically those occurring at puberty. The study will examine the effects of administering small concentrations of the amino acids into localized areas of the hypothalamus. Experiments are designed to determine a direct effect of the amino acids on the anterior pituitary gland. Amino acid transmitters examined are: GABA, glycine, taurine, beta-alanine, lysine, glutamate and aspartate. Experiments will employ the unrestrained-conscious animal with chronic indwelling cannulas permitting simultaneous blood withdrawal and sample infusion into the brain or pituitary. Blood hormone levels are determined by radioimmunoassay.